Multiple injection blend for direct injected engines

Abstract

A fuel injection system for a direct fuel injection engine is provided. The system includes an injection mode module that selects a fuel injection mode to be one of a single injection mode and a dual injection mode during engine operation and a fuel injection command module that commands fuel injection events based on a crankshaft position, the fuel injection mode and a fuel percentage blending schedule.

1. A fuel injection system for a direct fuel injection engine, comprising:
 an injection mode module that selects a fuel injection mode to be one of a single injection mode and a dual injection mode during engine operation; and 
 a fuel injection command module that commands fuel injection events based on a crankshaft position, the fuel injection mode and a fuel percentage blending schedule. 
 
     
     
       2. The system of  claim 1  wherein the fuel injection command module commands fuel at a first rate when the crankshaft position is within a first predetermined range during the single injection mode. 
     
     
       3. The system of  claim 2  wherein the first predetermined range is between two hundred and fifty and three hundred and eighty crank rotation degrees before spark is commanded near top dead center. 
     
     
       4. The system of  claim 1  wherein the fuel injection command module transitions fuel command to a second rate and at a third rate based on the fuel percentage blending schedule. 
     
     
       5. The system of  claim 4  wherein the fuel injection command module commands fuel at the second rate and the third rate when the crankshaft position signal indicates a crankshaft position within second and third predetermined ranges respectively during the dual injection mode. 
     
     
       6. The system of  claim 5  wherein the second predetermined range is between two hundred and fifty and three hundred and eighty crank rotation degrees before spark is commanded near top dead center. 
     
     
       7. The system of  claim 5  wherein the third predetermined range is between zero and one hundred and eighty crank rotation degrees before spark is commanded near top dead center. 
     
     
       8. The system of  claim 4  wherein the fuel injection command module determines the second and the third rates based on a total fuel required for each intake and compression cycle. 
     
     
       9. The system of  claim 4  wherein the second rate and the third rate are based on a first and a second predetermined percentage of the total fuel required for the intake and compression cycles, wherein the first predetermined percentage is between fifty and one hundred percent and the second predetermined percentage is between fifty and one hundred percent. 
     
     
       10. A fuel injection method for a direct fuel injection engine, comprising:
 operating the engine in a single injection mode; 
 commanding fuel at a first rate during an intake cycle; 
 receiving a request to transition from a single injection mode to a dual injection mode; and 
 transitioning to the dual injection mode by commanding fuel at a second rate and at a third rate during the intake and compression cycles, wherein the second rate is decreased and the third rate is increased during subsequent cycles until target second and third rates are reached. 
 
     
     
       11. The method of  claim 10  wherein the commanding fuel at a first rate and the commanding fuel at a second and at a third rate is based on a crankshaft position. 
     
     
       12. The method of  claim 11  wherein the commanding fuel at a first rate further includes commanding fuel at a first rate when the crankshaft position is within a first predetermined range during the intake cycle of an engine cylinder. 
     
     
       13. The method of  claim 11  wherein the commanding fuel at a second rate and at a third rate further includes commanding fuel at a second rate when the crankshaft position is within a second predetermined range and commanding fuel at a third rate when the crankshaft position is within a third predetermined range during the intake and compression cycles of the engine cylinder. 
     
     
       14. The method of  claim 10  further including commanding spark when the crankshaft position is near top dead center during the single injection mode and the dual injection mode. 
     
     
       15. The method of  claim 10  wherein the commanding fuel at a first rate further includes commanding fuel at a first rate when an engine crankshaft position is within a range of two hundred and fifty and three hundred and eighty degrees of crank rotation before top dead center. 
     
     
       16. The method of  claim 10  wherein the commanding fuel at a second rate further includes commanding fuel at a second rate when an engine crankshaft position is within a range of two hundred and fifty and three hundred and eighty degrees of crank rotation before top dead center and wherein the commanding fuel at a third rate further comprises commanding fuel at a third rate when a crankshaft position is within a range of zero and one hundred and eighty degrees of crank rotation before top dead center. 
     
     
       17. The method of  claim 10  wherein the commanding fuel at a second rate is based on a predetermined percentage of a total fuel desired for the intake and compression cycles. 
     
     
       18. The method of  claim 17  wherein the commanding fuel at a second rate is based on the predetermined percentage of total fuel desired that begins at one hundred percent and is reduced to a value as low as fifty percent during the transition to the dual injection mode. 
     
     
       19. The method of  claim 18  wherein the commanding fuel at a third rate is based on a predetermined percentage that begins at zero percent and is increased to a value as great as fifty percent during the transition to the dual injection mode. 
     
     
       20. The method of  claim 10  wherein the commanding fuel at the third rate is based on a predetermined percentage of a total fuel desired for the intake and compression cycles. 
     
     
       21. The method of  claim 20  wherein the commanding fuel at the third rate is based on the predetermined percentage that is between zero and fifty percent of total fuel desired for the intake and compression cycles.